Urinary leukotriene E4 after lysine-aspirin inhalation in asthmatic subjects

Aspirin Intolerance: Experimental Models for Bed-to-Bench

Aspirin is the oldest non-steroidal anti-inflammatory drug (NSAID), and it sometimes causes asthma-like symptoms known as aspirin-exacerbated respiratory disease (AERD), which can be serious. Unwanted effects of aspirin (aspirin intolerance) are also observed in patients with food-dependent exercise-induced anaphylaxis, a type I allergy disease, and aspirin-induced urticaria (AIU). However the target and the mechanism of the aspirin intolerance are still unknown. There is no animal or cellular model of AERD, because its pathophysiological mechanism is still unknown, but it is thought that inhibition of cyclooxygenase by causative agents leads to an increase of free arachidonic acid, which is metabolized into cysteinyl leukotrienes (cysLTs) that provoke airway smooth muscle constriction and asthma symptoms. As the bed-to-bench approach, to confirm the clinical discussion in experimental cellular models, we have tried to develop a cellular model of AERD using activated RBL-2H3 cells, a rat mast cell like cell line. Indomethacin (another NSAID and also causes AERD), enhances in vitro cysLTs production by RBL-2H3 cells, while there is no induction of cysLTs production in the absence of inflammatory activation. Since this suggests that all inflammatory cells with activation of prostaglandin and cysLT metabolism should respond to NSAIDs, and then I have concluded that aspirin intolerance should be separated from subsequent bronchoconstriction. Evidence about the cellular mechanisms of NSAIDs may be employed for development of in vitro AERD models as the approach from bench-to-bed.

Mast cells in asthma--state of the art

Mast cells (MCs) play a central role in tissue homoeostasis, sensing the local environment through numerous innate cell surface receptors. This enables them to respond rapidly to perceived tissue insults with a view to initiating a co-ordinated programme of inflammation and repair. However, when the tissue insult is chronic, the ongoing release of multiple pro-inflammatory mediators, proteases, cytokines and chemokines leads to tissue damage and remodelling. In asthma, there is strong evidence of ongoing MC activation, and their mediators and cell-cell signals are capable of regulating many facets of asthma pathophysiology. This article reviews the evidence behind this.

Platelet activation markers overexpressed specifically in patients with aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is characterized by respiratory reactions on ingestion of COX-1 inhibitors and cysteinyl leukotriene overproduction. The hypersensitivity reaction is induced by low doses of aspirin that inhibit COX-1 in platelets.

OBJECTIVE

We sought to explore the role of platelets in the pathogenesis of AERD in patients under stable conditions and during an aspirin challenge test.

METHODS

Stable patients with AERD (n = 30), aspirin-tolerant asthma (ATA; n = 21), or idiopathic chronic eosinophilic pneumonia (n = 10) were enrolled. Platelet activation was estimated based on expression levels of P-selectin (CD62P), CD63, CD69, and GPIIb/IIIa (PAC-1) in peripheral platelets; percentages of circulating platelet-adherent leukocytes; and plasma levels of soluble P-selectin (sP-selectin) and soluble CD40 ligand (sCD40L).

RESULTS

In the stable condition, expression of all surface markers on platelets, the percentage of platelet-adherent eosinophils, and the plasma levels of sP-selectin and sCD40L were significantly higher in patients with AERD compared with those in patients with ATA. P-selectin and CD63 expression on platelets and plasma sP-selectin and sCD40L levels were positively correlated with the percentage of platelet-adherent eosinophils. Among these markers, P-selectin expression and plasma sP-selectin levels positively correlated with urinary concentrations of leukotriene E4. Additionally, plasma sP-selectin and sCD40L levels were negatively correlated with lung function. In contrast, platelet activation markers in patients with AERD did not change during the aspirin challenge test.

CONCLUSION

Peripheral platelets were activated more in patients with stable AERD compared with those in patients with stable ATA, patients with idiopathic chronic eosinophilic pneumonia, and control subjects. Platelet activation was involved in cysteinyl leukotriene overproduction and persistent airflow limitations in patients with AERD.

Aspirin-intolerant asthma: a comprehensive review of biomarkers and pathophysiology

Aspirin-exacerbated respiratory disease is a tetrad of nasal polyps, chronic hypertrophic eosinophilic sinusitis, asthma, and sensitivity to aspirin. Unawareness of this clinical condition by patients and physicians may have grave consequences because of its association with near-fatal asthma. The pathogenesis of aspirin-intolerant asthma is not related with an immunoglobin E mechanism, but with an abnormal metabolism of the lipoxygenase (LO) and cyclooxygenase (COX) pathways. At present, a diagnosis of aspirin sensitivity can be established only by provocative aspirin challenge, which represents a health risk for the patient. This circumstance has encouraged the search for aspirin intolerance-specific biomarkers. Major attempts have focused on mediators related with inflammation and eicosanoid regulation. The use of modern laboratory techniques including high-throughput methods has facilitated the detection of dozens of biological metabolites associated with aspirin-intolerant asthma disease. Not surprisingly, the majority of these is implicated in the LO and COX pathways. However, substantial amounts of data reveal the participation of many genes deriving from different ontologies. Biomarkers may represent a powerful, noninvasive tool in the diagnosis of aspirin sensitivity; moreover, they could provide a new way to classify asthma phenotypes.

Variants of CEP68 gene are associated with acute urticaria/angioedema induced by multiple non-steroidal anti-inflammatory drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are the most consumed drugs worldwide because of their efficacy and utility in the treatment of pain and inflammatory diseases. However, they are also responsible for an important number of adverse effects including hypersensitivity reactions. The most important group of these reactions is triggered by non-immunological, pharmacological mechanisms catalogued under the denomination of cross-intolerance (CRI), with acute urticaria/angioedema induced by multiple NSAIDs (MNSAID-UA) the most frequently associated clinical entity. A recent genome-wide association study identified the gene encoding the centrosomal protein of 68 KDa (CEP68) as the major locus associated with aspirin intolerance susceptibility in asthmatics. In this study, we aimed to assess the role of this locus in susceptibility to CRI to NSAIDs by examining 53 common gene variants in a total of 635 patients that were classified as MNSAID-UA (n = 399), airway exacerbations (n = 110) or blended pattern (n = 126), and 425 controls. We found in the MNSAID-UA group a number of variants (17) associated (lowest p-value = 1.13×10⁻⁶), including the non-synonymous Gly74Ser variant (rs7572857) previously associated with aspirin intolerance susceptibility in asthmatics. Although not being significant in the context of multiple testing, eight of these variants were also associated with exacerbated respiratory disease or blended reactions. Our results suggest that CEP68 gene variants may play an important role in MNSAID-UA susceptibility and, despite the different regulatory mechanisms involved depending on the specific affected organ, in the development of hypersensitivity reactions to NSAIDs.

Genome-wide association study in NSAID-induced acute urticaria/angioedema in Spanish and Han Chinese populations

AIM

Acute urticaria/angioedema (AUA) induced by cross-intolerance to NSAIDs is the most frequent clinical entity in hypersensitivity reactions to drugs. In this work, we conducted a genome-wide association study in Spanish and Han Chinese patients suffering from NSAID-induced AUA.

MATERIALS & METHODS

A whole-genome scan was performed on a total of 232 cases (112 Spanish and 120 Han Chinese) with NSAID-induced AUA and 225 unrelated controls (124 Spanish and 101 Han Chinese).

RESULTS

Although no polymorphism reached genome-wide significance, we obtained suggestive associations for three clusters in the Spanish group (RIMS1, BICC1 and RAD51L 1) and one region in the Han Chinese population (ABI3BP). Five regions showed suggestive associations after meta-analysis: HLF, RAD51L1, COL24A1, GalNAc-T13 and FBXL7. A majority of these genes are related to Ca(2+), cAMP and/or P53 signaling pathways.

CONCLUSION

The associations described were different from those related to the metabolism of arachidonic acid and could provide new mechanisms underlying NSAID-induced AUA.

Identification of GPR99 protein as a potential third cysteinyl leukotriene receptor with a preference for leukotriene E4 ligand

The cysteinyl leukotrienes (cys-LTs), leukotriene C4 (LTC4), a conjugation product of glutathione and eicosatetraenoic acid, and its metabolites, LTD4 and LTE4, are lipid mediators of smooth muscle constriction and inflammation in asthma. LTD4 is the most potent ligand for the type 1 cys-LT receptor (CysLT1R), and LTC4 and LTD4 have similar lesser potency for CysLT2R, whereas LTE4 has little potency for either receptor. Cysltr1/Cysltr2(-/-) mice, lacking the two defined receptors, exhibited a comparable dose-dependent vascular leak to intradermal injection of LTC4 or LTD4 and an augmented response to LTE4 as compared with WT mice. As LTE4 retains a cysteine residue and might provide recognition via a dicarboxylic acid structure, we screened cDNAs within the P2Y nucleotide receptor family containing CysLTRs and dicarboxylic acid receptors with trans-activator reporter gene assays. GPR99, previously described as an oxoglutarate receptor (Oxgr1), showed both a functional and a binding response to LTE4 in these transfectants. We generated Gpr99(-/-) and Gpr99/Cysltr1/Cysltr2(-/-) mice for comparison with WT and Cysltr1/Cysltr2(-/-) mice. Strikingly, GPR99 deficiency in the Cysltr1/Cysltr2(-/-) mice virtually eliminated the vascular leak in response to the cys-LT ligands, indicating GPR99 as a potential CysLT3R active in the Cysltr1/Cysltr2(-/-) mice. Importantly, the Gpr99(-/-) mice showed a dose-dependent loss of LTE4-mediated vascular permeability, but not to LTC4 or LTD4, revealing a preference of GPR99 for LTE4 even when CysLT1R is present. As LTE4 is the predominant cys-LT species in inflamed tissues, GPR99 may provide a new therapeutic target.

A review on herbal antiasthmatics

In traditional systems of medicine, many plants have been documented to be useful for the treatment of various respiratory disorders including asthma. In the last two decades the use of medicinal plants and natural products has been increased dramatically all over the world. Current synthetic drugs used in pharmacotherapy of asthma are unable to act at all the stages and targets of asthma. However some herbal alternatives employed in asthma are proven to provide symptomatic relief and assist in the inhibition of disease progression also. The herbs have shown interesting results in various target specific biological activities such as bronchodilation, mast cell stabilization, anti-anaphylactic, anti-inflammatory, anti-spasmodic, anti-allergic, immunomodulatory and inhibition of mediators such as leukotrienes, lipoxygenase, cyclooxygenase, platelet activating, phosphodiesterase and cytokine, in the treatment of asthma. This paper is an attempt to classify these pharmacological and clinical findings based on their possible mechanism of action reported. It also signifies the need for development of polyherbal formulations containing various herbs acting at particular sites of the pathophysiological cascade of asthma for prophylaxis as well as for the treatment of asthma.

Leukotriene modifiers for asthma treatment

Leukotrienes (LTs), including cysteinyl LTs (CysLTs) and LTB(4) , are potent lipid mediators that have a role in the pathophysiology of asthma. At least two receptor subtypes for CysLTs, CysLT(1) and CysLT(2) , have been identified. The activation of the CysLT(1) receptor is responsible for most of the pathophysiological effects of CysLTs in asthma, including increased airway smooth muscle activity, microvascular permeability, and airway mucus secretion. LTB(4) might have a role in severe asthma, asthma exacerbations, and the development of airway hyperresponsiveness. CysLT(1) receptor antagonists can be given orally as monotherapy in patients with mild persistent asthma, but these drugs are generally less effective than inhaled glucocorticoids. Combination of CysLT(1) receptor antagonists and inhaled glucocorticoids in patients with more severe asthma may improve asthma control and enable the dose of inhaled glucocorticoids to be reduced while maintaining similar efficacy. The identification of subgroups of asthmatic patients who respond to CysLT(1) receptor antagonists is relevant for asthma management as the response to these drugs is variable. CysLT(1) receptor antagonists have a potential anti-remodelling effect that might be important for preventing or reversing airway structural changes in patients with asthma. This review discusses the role of LTs in asthma and the role of LT modifiers in asthma treatment.

Leukotriene E4-induced pulmonary inflammation is mediated by the P2Y12 receptor

Of the potent lipid inflammatory mediators comprising the cysteinyl leukotrienes (LTs; LTC₄, LTD₄, and LTE₄), only LTE₄ is stable and abundant in vivo. Although LTE₄ shows negligible activity at the type 1 and 2 receptors for cys-LTs (CysLT₁R and CysLT₂R), it is a powerful inducer of mucosal eosinophilia and airway hyperresponsiveness in humans with asthma. We show that the adenosine diphosphate (ADP)–reactive purinergic (P2Y₁₂) receptor is required for LTE₄-mediated pulmonary inflammation. P2Y₁₂ receptor expression permits LTE₄ -induced activation of extracellular signal-regulated kinase in Chinese hamster ovary cells and permits chemokine and prostaglandin D₂ production by LAD2 cells, a human mast cell line. P2Y₁₂ receptor expression by LAD2 cells is required for competition between radiolabeled ADP and unlabeled LTE₄ but not for direct binding of LTE₄, suggesting that P2Y₁₂ complexes with another receptor to recognize LTE₄. Administration of LTE₄ to the airways of sensitized mice potentiates eosinophilia, goblet cell metaplasia, and expression of interleukin-13 in response to low-dose aerosolized allergen. These responses persist in mice lacking both CysLT₁R and CysLT₂R but not in mice lacking P2Y₁₂ receptors. The effects of LTE₄ on P2Y₁₂ in the airway were abrogated by platelet depletion. Thus, the P2Y₁₂ receptor is required for proinflammatory actions of the stable abundant mediator LTE₄ and is a novel potential therapeutic target for asthma.

Aspirin-sensitive respiratory disease

Aspirin-sensitive respiratory disease (ASRD) is a condition characterized by persistent and often severe inflammation of the upper and lower respiratory tracts. Patients develop chronic eosinophilic rhinosinusitis, nasal polyposis, and asthma. The ingestion of aspirin and other cyclooxygenase-1 (COX-1) inhibitors induces exacerbations of airway disease that may be life-threatening. Thus, aspirin sensitivity is a phenotypic marker for the syndrome, yet nearly all affected individuals can be desensitized by the administration of graded doses of aspirin, leading to long-term clinical benefits. Patients with aspirin sensitivity are often able to tolerate selective COX-2 inhibitors. The pathogenesis of ASRD is underpinned by abnormalities in eicosanoid biosynthesis and eicosanoid receptor expression coupled with intense mast cell and eosinophilic infiltration of the entire respiratory tract. This review focuses on the molecular, cellular, and biochemical abnormalities characterizing ASRD and highlights unanswered questions in the literature and potential future areas of investigation.

Leukotriene E4: perspective on the forgotten mediator

Leukotriene (LT) E(4) mediates many of the principal features of bronchial asthma, such as bronchial constriction, hyperresponsiveness, eosinophilia, and increased vascular permeability. Furthermore, it is the most stable of the cysteinyl leukotrienes (CysLTs) and can be active at the site of release for a prolonged time after its synthesis. There might be several reasons why LTE(4) has been forgotten. LTE(4) demonstrated low affinity for CysLT(1) and CysLT(2) receptors in equilibrium competition assays. It was less potent than other CysLTs in functional assays, such as calcium flux, in cells transfected with CysLT(1) and CysLT(2). The introduction of CysLT(1) antagonists into clinical practice diverted interest into CysLT(1)-related mechanisms, which were mediated mainly by LTD(4). However, experiments with animal models and human studies have revealed that LTE(4) has unique characteristics that cannot be explained by the current knowledge of CysLT(1) and CysLT(2). These activities include its potency relative to other CysLTs to increase airway responsiveness to histamine, to enhance eosinophilic recruitment, and to increase vascular permeability. Asthmatic airways also demonstrate marked in vivo relative hyperresponsiveness to LTE(4), especially in patients with aspirin-sensitive respiratory disease. This has stimulated a search for additional LT receptors that would respond preferentially to LTE(4) stimulation.

Safety of triflusal (antiplatelet drug) in patients with aspirin-exacerbated respiratory diseases

BACKGROUND AND AIMS

Aspirin, a cyclo-oxygenase (COX)-1 and COX-2 inhibitor, is the antiplatelet drug of choice to prevent serious vascular events. Adverse reactions to aspirin are frequent particularly among patients with asthma, chronic rhinosinusitis and nasal polyps. COX-1 inhibitors but not COX-2 inhibitors precipitate asthma attacks. Triflusal is a preferential COX-2 inhibitor antiplatelet agent that is as effective as aspirin in the prevention of serious vascular events. The aim of the study was to assess the tolerability of triflusal in patients with aspirin-exacerbated respiratory disease (AERD).

METHODS

We studied 26 asthma patients [11 males, aged 52 (23-75) years] who had suffered asthma episodes triggered by one or more (23% of patients) nonsteroidal anti-inflammatory drugs. Aspirin sensitivity was confirmed by either intranasal or oral aspirin challenge. All subjects underwent a single-blind, placebo-controlled oral challenge with three doses of triflusal separated by 1 week (first cumulative dose = 225 mg; second cumulative dose = 450 mg; third cumulative dose = 900 mg). Cutaneous, respiratory, general symptoms and lung function were monitored for 4 h in the laboratory and for 24 h at home.

RESULTS

No clinical reactions to triflusal were observed. There were no significant changes in lung function measurements.

CONCLUSION

Our study appears to demonstrate that triflusal is a suitable alternative to aspirin as antiplatelet agent to prevent AERD.

PGE suppresses excessive anti-IgE induced cysteinyl leucotrienes production in mast cells of patients with aspirin exacerbated respiratory disease

BACKGROUND

Aspirin causes bronchospasm in patients with aspirin exacerbated respiratory disease (AERD). The contribution of mast cells to the increased cysteinyl-leucotrienes (cys-LTs) detected in AERD patients is however not defined.

AIMS OF THE STUDY

Effects of prostaglandin (PG) E(2) and inhibitors of cyclooxygenase (COX) and lipoxygenase (LO) pathways on mediator release from cultured mast cells of normal subjects, aspirin tolerant asthma (ATA) and AERD patients were compared to better define the role of mast cells in AERD.

METHODS

Mast cells were cultured from peripheral blood progenitors and were activated by anti-IgE. Histamine, PGD(2) and cys-LTs released were then determined.

RESULTS

Basal release of all three mediators was similar in all subjects. Although the release of all three mediators was increased by anti-IgE, mast cells from AERD patients produced significantly more cys-LTs (6.9 +/- 2.0 ng/10(6) cells) than normal and ATA subjects (2.3 +/- 0.8 and 1.7 +/- 0.5 ng/10(6) cells, respectively). While COX and LO pathway inhibitors did not affect anti-IgE induced histamine release, they significantly suppressed the production of PGD(2) and cys-LTs, respectively, in all patients. PGE(2) significantly enhanced anti-IgE induced histamine and PGD(2) release from mast cells of normal subjects but not those of ATA and AERD patients. In contrast, PGE(2) suppressed only anti-IgE induced cys-LTs release from mast cells of AERD patients.

CONCLUSION

We speculate that overproduction of cys-LTs is unique to mast cells of AERD patients and is particularly sensitive to suppression by PGE(2). Consequently reduction of PGE(2) production by aspirin removes this endogenous control of cys-LTs overproduction, resulting in asthma attack.

Cysteinyl leukotriene receptor 1 promoter polymorphism is associated with aspirin-intolerant asthma in males

BACKGROUND

Cysteinyl leukotrienes (CysLTs) play important roles in the pathogenesis of eosinophilic airway inflammation characterized by bronchoconstriction, mucus secretion and airway hyper-responsiveness via cysteinyl leukotriene receptor 1 (CysLTR1)-mediated mechanism. CysLTR1-selective antagonists have anti-bronchoconstrictive and anti-inflammatory effects in asthma, particularly aspirin-intolerant asthma (AIA).

METHODS

To investigate the association of CysLTR1 with AIA development, we identified three single nucleotide polymorphisms (SNPs), -634C>T, -475A>C, -336A>G, in the 5' upstream region of CysLTR1 gene using a direct sequencing method in 105 AIA patients, 110 ASA-tolerant asthma (ATA) patients and 125 normal healthy controls (NC).

RESULTS

Significant differences were observed in allele frequencies of the three SNPs within male subjects; Male AIA patients had higher frequencies of the minor alleles of these three SNPs than male control groups (P=0.03 for AIA vs. NC; P=0.02 for AIA vs. ATA). Moreover, three-SNP haplotype, ht2 [T-C-G], was associated with increased disease risk (odds ratio (OR)=2.71, P=0.03 for AIA vs. NC; OR=2.89, P=0.02 for AIA vs. ATA) in males. CysLTR1 haplotypes were also associated with altered gene expression; luciferase activity was significantly enhanced with the ht2 [T-C-G] construct in comparison with the ht1 [C-A-A] construct in human Jurkat cells (P=0.04).

CONCLUSION

These results suggest that genetic variants of CysLTR1 are associated with AIA in a Korean population, and may modulate CysLTR1 expression.

Leukotriene-related gene polymorphisms in patients with aspirin-intolerant urticaria and aspirin-intolerant asthma: differing contributions of ALOX5 polymorphism in Korean population

The pathogenesis of aspirin (acetylsalicylic acid, ASA)-intolerant urticaria (AIU) is still poorly understood but it has recently been suggested that it is associated with the overproduction of leukotriene (LT). This is supported by evidence that cyclooxygenase 2 inhibitor is given safely to patients with AIU. The present study was designed to investigate the role of genetic polymorphism of LT related genes in the pathogenesis of AIU via a case-control study. We screened single nucleotide polymorphisms (SNPs) in genes encoding enzymes involved in leukotriene synthesis in the Korean population with AIU (n = 101), ASA-intolerant asthma (AIA, n = 95) and normal healthy controls (n = 123). Genotype was determined by primer extension reactions using the SNapShot ddNTP primer extension kit. Among 8 SNPs of four LT related genes, the polymorphism of ALOX5 at positions of -1708 G > A showed significant difference in genotype frequency between AIU and AIA (p = 0.01). Furthermore, there were significant differences observed in the frequencies of two ALOX5 haplotypes between the AIU group and AIA group (p < 0.05). However, there were no differences in allele, genotype, or haplotype frequencies of ALOX5 between the AIU group and the normal control group. These results suggested that ALOX5 has a differing contribution in two major clinical pathogenesis related to ASA-sensitivity.

Association of thromboxane A2 receptor gene polymorphism with the phenotype of acetyl salicylic acid-intolerant asthma

BACKGROUND AND OBJECTIVE

The thromboxane A2 receptor (TBXA2R) is a receptor for a potent bronchoconstrictor, TBXA2 which is known to be related to bronchial asthma and myocardial infarction. TBXA2R antagonist and TBX synthase inhibitors have been found to be effective in the management of asthmatic patients. This study was aimed to evaluate whether genetic variants of TBXA2R may be related with development of acetyl salicylic acid (ASA)-intolerant asthma (AIA).

METHODS

TBXA2R gene polymorphisms (TBXA2R+795T>C, TBXA2R+924T>C) were determined using a single-base extension method in 93 AIA patients compared with 172 patients with ASA-tolerant asthma (ATA) and 118 normal controls (NCs) recruited from the Korean population. HLA DPB1*0301 genotype was performed using a direct sequencing method.

RESULTS

The rare C allele frequency of TBXA2R+795T>C was significantly higher in AIA than in ATA (P=0.03) and the TBXA2R+795T>C polymorphism was also associated with extent of percent fall in forced expiratory volume in 1 s (FEV1) after the inhalation of lysine-acetyl salicylic acid in AIA patients (P=0.009); AIA patients homozygous for the +795 C allele had a greater percent fall of FEV1 compared with individuals with TBXA2R+795 CT or TT genotypes. The frequency of patients carrying both the TBXA2R+795T>C rare allele and HLA DPB1(*)0301 was significantly higher in AIA patients (29.4%) than in ATA patients (7.3%) (P=0.008, odds ratio=5.3).

CONCLUSION

These results suggest that the polymorphism of TBXA2R+795T>C may increase bronchoconstrictive response to ASA, which could contribute to the development of the AIA phenotype.

Aspirin-triggered 15-HETE generation in peripheral blood leukocytes is a specific and sensitive Aspirin-Sensitive Patients Identification Test (ASPITest)

BACKGROUND

We have previously demonstrated that aspirin triggers specific generation of 15-hydroxyeicosateraenoic acid (15-HETE) from nasal polyp epithelial cells and peripheral blood leukocytes (PBL) from aspirin-sensitive (AS) but not aspirin-tolerant (AT) patients with asthma/rhinosinusitis. The goal of this study was to assess the diagnostic value of ASA-induced 15-HETE generation measurement to identify AS patients.

METHODS

PBL were obtained from 43 AS patients with asthma and rhinosinusitis, 35 AT asthmatics and 17 healthy control (HC) subjects. PBL were incubated with 2-200 muM aspirin (ASA) and 15-HETE release was measured in cell supernatants with competitive ELISA.

RESULTS

Unstimulated PBL from all three groups of patients generated similar amount of 15-HETE. Incubation with 200 microM ASA resulted in an increase in an 15-HETE generation (mean increase +421%) in AS-asthmatics but small and nonsignificant response in AT-asthmatics or control subjects. Receiver operating curve (ROC) analysis revealed that the sensitivity of the test for confirmation of ASA-sensitivity was 83% and the specificity 82%. Positive predictive value was 0.79 and negative predictive value was 0.86. Naproxen induced a significant increase in 15-HETE only in some AS-asthmatics, but not in AT-asthmatics.

CONCLUSION

Our data demonstrate that ASA-induced 15-HETE generation by PBL is a specific and sensitive aspirin-sensitive patients identification test (ASPITest).

Failure of tacrolimus to prevent aspirin-induced respiratory reactions in patients with aspirin-exacerbated respiratory disease

BACKGROUND

In patients with aspirin-exacerbated respiratory disease (AERD), pretreatment with asthma controller medications (leukotriene modifiers, inhaled or systemic corticosteroids, and salmeterol) partially modifies the severity of aspirin-induced asthmatic reactions.

OBJECTIVE

A recent study showed that pretreatment with tacrolimus completely prevented aspirin-induced respiratory reactions and might allow silent aspirin desensitization.

METHODS

Ten patients with rhinosinusitis, nasal polyps, and asthma had a history of asthma attacks after ingesting aspirin and nonsteroidal anti-inflammatory drugs. All underwent baseline oral aspirin challenges and had typical respiratory reactions. They were then randomized to receive tacrolimus (0.1 mg/kg weight; 8 patients) or placebo (2 patients) in a double-blind protocol before rechallenge with aspirin using the previous provoking dose of aspirin. In addition, respiratory reactions sustained by 50 consecutive patients with AERD during 2004 were recorded, analyzed, and compared with the tacrolimus/placebo-treated patients to determine whether there were any differences.

RESULTS

Tacrolimus pretreatment failed to block respiratory reactions to provoking doses of aspirin in 5 of 8 patients with AERD, and in the other 3 patients did not block higher doses of aspirin. The results of oral aspirin challenges in the control population of 50 patients were compared with either the baseline or postchallenge data from the tacrolimus-pretreated or placebo-pretreated patients with AERD, and there were no significant differences.

CONCLUSIONS

Use of tacrolimus as add-on pretreatment to prevent reactions to aspirin in patients with AERD or to achieve the goal of silent aspirin desensitization could not be accomplished.

Polymorphism of tandem repeat in promoter of 5-lipoxygenase in ASA-intolerant asthma: a positive association with airway hyperresponsiveness

BACKGROUND

5-Lipooxygenase (ALOX5) and 5-lipoxygenase-activating protein (ALOX5AP) are known as key enzymes in cysteinyl-leukotriene (cys-LT) production, critical mediators in aspirin acetylsalicyclic acid (ASA)-intolerant asthma (AIA). To date, studies of the promoter region of ALOX5 gene has revealed the potential influence of a variable number of tandem repeats of a Sp1- and Egr1-binding motif, on the transcription rate.

METHODS

To understand the pathological process that arises from cys-LT overproduction in AIA, we genotyped ALOX5 Sp1 and ALOX5AP poly(A) repeat promoter polymorphism by fluorescent-based capillary electrophoresis in the Korean population.

RESULTS

No significant differences in allele and genotype frequencies of the ALOX5 and ALOX5AP promoter polymorphisms were observed between the three groups. However, there was a strong association of the ALOX5 Sp1 repeat polymorphism with airway hyperresponsiveness (AHR; PC20 methacholine); AIA patients carrying a mutant allele (n > 5 or n < 5 repeats) showed increased AHR compared to AIA patients with wild-type genotype (P=0.003).

CONCLUSION

Although the alleles of the ALOX5 and ALOX5AP promoter cannot be considered as a prominent risk factor in the development of AIA, the genetic variant of tandem repeat (GGGCGG; Sp1-binding motif) in ALOX5 promoter is associated with the severity of airway hyperresponsiveness in AIA patients.

Expression of the cysteinyl leukotriene receptors cysLT(1) and cysLT(2) in aspirin-sensitive and aspirin-tolerant chronic rhinosinusitis

BACKGROUND

Cysteinyl leukotrienes play a disease-regulating role in rhinosinusitis and asthma, particularly aspirin-sensitive disease. They act through 2 G-protein coupled receptors termed cysteinyl leukotriene type 1 receptor (cysLT 1 ) and cysteinyl leukotriene type 2 receptor (cysLT 2 ). We previously compared expression of cysLT 1 on mucosal leukocytes in patients with aspirin-sensitive and aspirin-tolerant rhinosinusitis.

OBJECTIVE

To compare expression of cysLT 1 and cysLT 2 on leukocytes, mucus glands, and epithelium in 32 patients with chronic polypoid rhinosinusitis (21 aspirin-sensitive, 11 aspirin-tolerant) and 9 normal controls.

METHODS

Total numbers of CD45 + leukocytes, percentages of these cells expressing cysLT 1 or cysLT 2 , and percentages of the total epithelial and glandular areas expressing cysLT 1 or cysLT 2 were measured in sections of nasal biopsies by using immunohistochemistry and image analysis.

RESULTS

The percentages of mucosal CD45 + leukocytes expressing cysLT 1 were significantly ( P < .0001) elevated in the aspirin-sensitive but not the aspirin-tolerant patients compared with the controls. In contrast, the percentages of leukocytes expressing cysLT 2 did not differ significantly in the 3 groups. On epithelial and glandular cells, expression of cysLT 2 significantly exceeded that of cysLT 1 in both the patients with rhinosinusitis and the controls ( P < or = .004), although there was no significant difference in the expression of either receptor in the patients with rhinosinusitis (aspirin-sensitive or aspirin-tolerant) and the controls.

CONCLUSION

Although cysLT 1 expression predominates on inflammatory leukocytes in patients with aspirin-sensitive rhinosinusitis, the effects of cysteinyl leukotrienes on glands and epithelium may be mediated predominantly through cysLT 2. This has potentially important therapeutic implications.

Increase in urinary leukotriene B4 glucuronide concentration in patients with aspirin-intolerant asthma after intravenous aspirin challenge

BACKGROUND

Aspirin challenge of aspirin-intolerant asthma (AIA) patients causes a significant increase in leukotriene E4 (LTE4) concentration in urine. However, knowledge on leukotriene B4 (LTB4) generation in patients with AIA is insufficient. Recent research has demonstrated that exogenously administered LTB4 is excreted as glucuronide into the urine in human healthy subjects.

OBJECTIVE

The purpose of this study is to estimate urinary LTB4 glucuronide (LTBG) concentration in the clinically stable condition in healthy subjects and asthmatic patients and to investigate changes in urinary LTBG concentration in patients with AIA after aspirin challenge.

METHODS

A provocation test was performed by intravenous aspirin challenge. After urine was hydrolysed by beta-glucuronidase, the fraction containing LTB4 was purified by high-performance liquid chromatography and LTB4 concentration was quantified by enzyme immunoassay. Urinary LTBG concentration was calculated as the difference between the concentration obtained with hydrolysis and that without hydrolysis.

RESULTS

(1) After hydrolysis, the presence of urinary LTB4 was verified by gas chromatography-mass spectrometry-selected ion monitoring. (2) The urinary LTBG concentration was significantly higher in the asthmatic patients than in the healthy subjects (median, 5.37 pg/mg creatinine [range 1.2-13] vs. 3.32 pg/mg creatinine [range, 0.14-10.5], P = 0.0159). (3) The patients with AIA (n = 7), but not those with aspirin-tolerant asthma (n = 6), showed significant increases in LTBG and LTE4 excretions after aspirin challenge. (4) When the concentrations after aspirin challenge were analysed simultaneously, a significant linear correlation was observed between urinary LTBG concentration and urinary LTE4 concentration in patients with AIA (Spearman's rank correlation test, r = 0.817, P = 0.0003).

CONCLUSION

LTBG is present in human urine, albeit at a concentration lower than urinary LTE4. In addition to a marked increase in cysteinyl-leukotriene production, aspirin challenge induced LTB4 production in AIA patients.

Urinary 3-bromotyrosine and 3-chlorotyrosine concentrations in asthmatic patients: lack of increase in 3-bromotyrosine concentration in urine and plasma proteins in aspirin-induced asthma after intravenous aspirin challenge

BACKGROUND

Eosinophil peroxidase and myeloperoxidase halogenate tyrosine residues in plasma proteins and generate 3-bromotyrosine (BY) and 3-chlorotyrosine (CY), respectively.

OBJECTIVES

(1) To estimate urinary concentrations of BY and CY in asthmatic patients. (2) To investigate BY concentration in relation to urinary leukotriene E4 (LTE4) concentration in order to evaluate the activation of eosinophils in patients with aspirin-induced asthma (AIA).

METHODS

BY and CY were quantified with a gas chromatograph-mass spectrometer using (13)C-labelled compounds as internal standards.

RESULTS

(1) Activation of eosinophils and neutrophils by immobilized IgG1 induced preferential formation of BY and CY, respectively. (2) A significantly higher concentration of BY was observed in the urine from asthmatic patients than in that from healthy control subjects (45+/-21.7 vs. 22.6+/-10.8 ng/mg-creatinine, P<0.01). CY concentration was also elevated in the urine from asthmatic patients (4.4+/-3.2 vs. 1.5+/-1.0 ng/mg-creatinine, P<0.01). (3) After intravenous aspirin challenge of aspirin-induced asthmatic patients, the concentration of BY in urine did not significantly change. No significant change was also observed in the ratio of BY concentration to total tyrosine concentration in plasma proteins. In contrast, the concentration of urinary LTE4 significantly increased after the intravenous aspirin challenge.

CONCLUSION

Determination of BY and CY concentrations may be useful for monitoring the activation of eosinophils and neutrophils in asthmatic patients, respectively. After aspirin challenge of AIA patients, the increased concentration of urinary LTE4 did not accompany changes in BY concentration in both urine and plasma proteins. These results may preclude the activation of eosinophils after aspirin challenge in patients with AIA.

Urinary leukotriene E4 and 9 alpha, 11 beta-prostaglandin F concentrations in mild, moderate and severe asthma, and in healthy subjects

BACKGROUND

Airway inflammation in asthma is associated with cysteinyl leukotriene and prostaglandin D(2) production. Measurement of urinary metabolites of these eicosanoids may be useful for monitoring asthma patients. However, the influence of asthma phenotype and severity on basal urinary excretion of these metabolites is unknown.

OBJECTIVE

To compare urinary leukotriene (LT)E(4) and 9 alpha, 11 beta-prostaglandin (PG)F(2) concentrations in large groups of mild, moderate and severe asthmatic patients and healthy control subjects.

METHODS

Asthma severity, treatment and aspirin sensitivity were assessed by questionnaire in 168 asthmatic patients. Basal LTE(4) and 9 alpha, 11 beta-PGF(2) concentrations were measured in urine samples from these patients and from 175 control subjects using enzyme immunoassays.

RESULTS

Urinary LTE(4) was correlated with 9 alpha, 11 beta-PGF(2) in both control subjects and asthmatic patients (P<0.002). Median LTE(4) and 9 alpha, 11 beta-PGF(2) concentrations in patients with severe asthma were significantly reduced compared with mild asthmatic patients (P<0.05 and <0.001, respectively). Urinary 9 alpha, 11 beta-PGF(2), but not LTE(4) was lower in asthmatic patients using inhaled corticosteroids (P<0.02). Multiple regression analysis indicated that urinary 9 alpha, 11 beta-PGF(2) concentration was negatively correlated with asthma severity (P=0.003) and also with % predicted FEV(1) (forced expiratory volume in 1 s) (P=0.005).

CONCLUSIONS

Baseline urinary LTE(4) and 9 alpha, 11 beta-PGF(2) concentrations are of limited value in discriminating between patients with different severities of asthma. Reduced urinary LTE(4) and 9 alpha, 11 beta-PGF(2) in patients with severe asthma suggest that direct or indirect effects of high-dose corticosteroid therapy combined with other factors associated with severe asthma may influence eicosanoid production. However, the negative association of urinary 9 alpha, 11 beta-PGF(2) with lung function suggests an adverse effect of chronic PGD(2) production on lung function in asthma, irrespective of severity.

Leukotriene-receptor expression on nasal mucosal inflammatory cells in aspirin-sensitive rhinosinusitis

BACKGROUND

Patients with asthma who have aspirin sensitivity have greater cysteinyl leukotriene production and greater airway hyperresponsiveness to the effects of inhaled cysteinyl leukotrienes than their aspirin-tolerant counterparts. We hypothesized that the latter effect reflects elevated expression of the cysteinyl leukotriene receptor CysLT1 on inflammatory cells in the target organ and that its expression is down-regulated by aspirin desensitization.

METHODS

We obtained nasal-biopsy specimens from 22 aspirin-sensitive and 12 non-aspirin-sensitive patients with chronic rhinosinusitis and nasal polyps. Additional specimens were then obtained from subgroups of the aspirin-sensitive patients after intranasal application of lysine aspirin or placebo for two weeks (five and four patients, respectively) or for six months (five and four patients, respectively). The numbers of leukocytes expressing the CysLT1 and leukotriene B4 (LTB4) receptors per unit area of sections of the nasal submucosa were determined by immunohistochemistry.

RESULTS

The absolute number of cells expressing the CysLT1 receptor was significantly higher in the aspirin-sensitive patients than in the non-aspirin-sensitive patients (median, 542 cells per square millimeter [range, 148 to 1390] vs. 116 cells per square millimeter [range, 40 to 259]; P<0.001). The percentage of CD45+ leukocytes expressing the CysLT1 receptor was also higher in the aspirin-sensitive subjects (25 percent of CD45+ leukocytes [range, 4 to 50] vs. 5 percent of CD45+ leukocytes [range, 2 to 11]; P<0.001); the percentage of CD45+ leukocytes expressing the LTB4 receptor did not differ significantly between these two groups. Desensitization was associated with a decrease in the numbers of inflammatory cells expressing CysLT1.

CONCLUSIONS

The elevated numbers of nasal inflammatory leukocytes expressing the CysLT1 receptor in aspirin-sensitive patients with chronic rhinosinusitis as compared with their non-aspirin-sensitive counterparts and the down-regulation of receptor expression after desensitization to aspirin are probably fundamental in the pathogenesis of aspirin sensitivity and in the mechanism of aspirin desensitization.

Furosemide: progress in understanding its diuretic, anti-inflammatory, and bronchodilating mechanism of action, and use in the treatment of respiratory tract diseases

Accumulated experimental and clinical data suggest that adrenocorticosteroids and/or endogenous ouabain-like substances may play an important role in the mechanism of furosemide diuretic action. It was reported that the drug is highly bound in the adrenals, lungs, kidney, spleen, and liver. In patients with liver cirrhosis, furosemide exerted a markedly decreased natriuretic effect compared with normal subjects, and the plasma levels of circulating endothelin and atrial natriuretic factor (ANF) were significantly elevated. In neonates, after administration of furosemide, the urinary excretion of endothelin-1 and aldosterone increased markedly, and it is known that endothelin may release ANF and aldosterone in a dose-dependent manner. Furosemide was used to stimulate zona glomerulosa, whereas ANF decreased the production of steroids in zona glomerulosa and fasciculata cell culture owing to stimulation by various factors. Because the concomitant use of ANF and furosemide appeared to be diuretically effective in newborns after cardiac surgery, one may suggest that furosemide competes with ANF for its effects on the adrenals. Furosemide administered by inhalation exerted a protective effect on allergic and perennial nonallergic rhinitis and was effective in preventing the postsurgical recurrence of nasal polyposis. The drug can also be used as an antiasthmatic agent. In preterm ventilator-dependent infants with chronic lung disease, aerosolized furosemide improved pulmonary function with no marked effect on diuresis. In adults and children with asthma, furosemide exerted a protective effect against bronchoconstriction induced by several indirect stimuli similar to that of disodium cromoglycate or nedocromil. Aerosolized furosemide had a preventive effect also on bronchoconstriction induced by inhaled lysine acetylsalicylate in patients with aspirin-sensitive asthma. In high-dose beclomethasone-dependent asthma, inhaled lysine acetylsalicylate and furosemide exerted a mutually potentiating antiasthmatic activity, allowing considerable sparing of the inhaled steroid. It is proposed that this effect may be explained by the corticosteroid-sparing action of lysine released from the lysine acetylsalicylate molecule because similar beneficial effects were also obtained after the concomitant use of epsilon-aminocaproic acid (whose chemical structure is almost the same as that of lysine) and prednisone. Furosemide exhibited an anti-inflammatory effect through inhibition of production and release of cytokines interleukin (IL)-6, IL-8, and tumor necrosis factor-alpha from peripheral mononuclear cells, which may have a beneficial effect on local inflamed tissue imbalance in the ratio of different cytokines, thus improving the sensitivity of target cells to endogenous glucocorticosteroids.

Possible involvement of mast-cell activation in aspirin provocation of aspirin-induced asthma

BACKGROUND

Although there is increasing evidence of the importance of cysteinyl leukotrienes (LT) as mediators of aspirin-induced bronchoconstriction in aspirin-sensitive asthma, the cellular origin of the LT is not yet clear.

METHODS

Urinary concentrations of leukotriene E4 (LTE4), 11-dehydrothromboxane B2, 9alpha,11beta-prostaglandin F2, and Ntau-methylhistamine were measured during the 24 h following cumulative intravenous administration of increasing doses of lysine aspirin to asthmatic patients. In addition, the urinary concentrations of these metabolites were measured on 5 consecutive days in a patient who suffered an asthma attack after percutaneous administration of nonsteroidal anti-inflammatory drugs.

RESULTS

In aspirin-induced asthma patients (AIA, n=10), the basal concentration of urinary LTE4, but not the other metabolites, was significantly higher than that in aspirin-tolerant asthma patients (ATA, n=10). After intravenous aspirin provocation, the AIA group showed a 13.1-fold (geometric mean) increase in excretion of LTE4 during the first 3 h, and 9alpha,11beta-prostaglandin F2 also increased in the AIA group during the first 0-3 h and the 3-6 h collection period. Ntau-methylhistamine excretion was also increased, but to a lesser degree. Administration of aspirin caused significant suppression of 11-dehydrothromboxane B2 excretion in both the AIA and ATA groups. When the percentage of maximum increase of each metabolite from the baseline concentrations was compared between the AIA group and the ATA group, a significantly higher increase in excretion of LTE4, 9alpha,11beta-prostaglandin F2, and Ntau-methylhistamine was observed in the AIA group than the ATA group. An increased excretion of LTE4 and 9alpha,11beta-prostaglandin F2 has been detected in a patient who suffered an asthma attack after percutaneous administration of nonsteroidal anti-inflammatory drugs.

CONCLUSIONS

Considering that human lung mast cells are capable of producing LTC4, prostaglandin D2, and histamine, our present results support the concept that mast cells, at least, may participate in the development of aspirin-induced asthma.

Evidence of 5-lipoxygenase overexpression in the skin of patients with systemic sclerosis: a newly identified pathway to skin inflammation in systemic sclerosis

OBJECTIVE

Leukotrienes are a family of arachidonic acid derivatives with potent proinflammatory and profibrotic properties, and 5-lipoxygenase (5-LOX) catalyzes two key steps in the leukotriene biosynthetic pathway. Since inflammatory cell infiltrates and excessive fibrosis are hallmarks of systemic sclerosis (SSc) skin lesions, we undertook the present study to investigate the expression of 5-LOX in skin biopsy specimens from patients with SSc.

METHODS

Expression of 5-LOX in skin sections from 10 SSc patients and 8 healthy controls was examined by in situ hybridization with specific riboprobes and by immunohistochemistry analysis with 5-LOX monoclonal antibodies. Synthesis of 5-LOX by cultured dermal fibroblasts from 7 patients with SSc and 4 controls was measured by fluorescence-activated cell sorter analysis. In addition, concentrations of leukotriene B4 (LTB4) and LTE4 in fibroblast supernatants after stimulation were determined using enzyme immunoassays.

RESULTS

Expression of 5-LOX was found in all skin sections from SSc patients as well as from controls. However, the number and percentage of 5-LOX-positive cells were significantly higher in SSc skin sections compared with control sections. Expression of 5-LOX was seen in cells within perivascular inflammatory infiltrates as well as in fibroblasts throughout the skin. The experiments with cultured skin fibroblasts revealed that 5-LOX was constitutively expressed in these cells, which resulted in the production of leukotrienes after cell stimulation. Whereas no difference was found for LTE4, SSc fibroblasts produced significantly higher amounts of LTB4 after stimulation, compared with healthy control fibroblasts.

CONCLUSION

The results of this study suggest that the 5-LOX pathway may be of significance in the pathogenesis of SSc and may represent a target for new treatment strategies.

Aspirin and asthma

Aspirin is not only one of the best-documented medicines in the world, but also one of the most frequently used drugs of all times. In addition to its role as an analgesic, aspirin is being increasingly used in the prophylaxis of ischemic heart disease and strokes. The prevalence of aspirin intolerance is around 5 to 6%. Up to 20% of the asthmatic population is sensitive to aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) and present with a triad of rhinitis, sinusitis, and asthma when exposed to the offending drugs. This syndrome is referred to as aspirin-induced asthma (AIA). The pathogenesis of AIA has implicated both the lipoxygenase (LO) and the cyclooxygenase (COX) pathways. By inhibiting the COX pathway, aspirin diverts arachidonic acid metabolites to the LO pathway. This also leads to a decrease in the levels of prostaglandin (PG) E(2), the anti-inflammatory PG, along with an increase in the synthesis of cysteinyl leukotrienes (LTs). Evidence suggests that patients with AIA have increased activity of LTC(4) synthase, the rate-limiting enzyme in the cysteinyl LT synthesis, in their bronchial biopsy specimens, thereby tilting the balance in favor of inflammation. LT-modifying drugs are effective in blocking the bronchoconstriction provoked by aspirin and are used in the treatment of this condition. Aspirin desensitization has a role in the management of AIA, especially in patients who need prophylaxis from thromboembolic diseases, myocardial infarction, and stroke. This review covers the latest understanding of pathogenesis, clinical features, and management of AIA.

Differential metabolism of arachidonic acid in nasal polyp epithelial cells cultured from aspirin-sensitive and aspirin-tolerant patients

The mechanism of aspirin (acetylsalicylic acid [ASA]) sensitivity associated with severe asthma and chronic rhinosinusitis with nasal polyps ("aspirin triad") has been attributed to arachidonic metabolism alternations, although the putative biochemical defects have not been elucidated. The aim of this study was assessment of the hypothesis that local production of eicosanoids in the respiratory epithelium in patients with ASA-sensitive asthma/rhinosinusitis (ASARS) differs from that of ASA-tolerant patients with rhinosinusitis (ATRS). Nasal polyps were obtained from 10 patients with ASARS and 15 with ATRS during routine polypectomies, and epithelial cells (ECs) were cultured on bovine collagen type I matrix (Vitrogen 100), in medium supplemented with growth factors. The generation of eicosanoids in supernatants of confluent ECs (6 to 8 d of culture; purity > 98%) was quantified by immunoassays. Unstimulated ECs from ASARS patients generated significantly less prostaglandin E(2)(PGE(2)) compared with ATRS (0.8 +/- 0.3 versus 2. 4 +/- 0.5 ng/microg double-stranded deoxyribonucleic acid [dsDNA], respectively), although a similar relative increase in response to calcium ionophore and inhibition with ASA was observed in both groups. Basal levels of 15-hydroxyeicosatetraenoic acid (15-HETE) were not different between groups, and calcium ionophore enhanced its production to a similar extent. However, cells incubation with 200 microM ASA for 60 min resulted in a significant increase (mean +359%) in 15-HETE generation only in ASARS patients, whereas no effect of ASA on 15-HETE generation in ATRS patients was observed. PGF(2alpha) generation was similar in both groups, and no significant generation of PGD(2) or leukotriene C(4) (LTC(4)) was observed in epithelial cell cultures from either group. Our results indicate that nasal polyps ECs from ASA-sensitive patients have significant abnormality in basal and ASA-induced generation of eicosanoids which may be causally related to the mechanism of ASA sensitivity.

A six week double blind, placebo controlled, crossover study of the effect of misoprostol in the treatment of aspirin sensitive asthma

BACKGROUND

Prostaglandins of the E series and misoprostol (a stable analogue of prostaglandin E(1)) prevent bronchoconstriction following aspirin ingestion or inhalation in subjects with aspirin sensitive asthma. A study was undertaken to investigate the influence of misoprostol on the course of aspirin induced asthma.

METHODS

A double blind, crossover, randomised, placebo controlled study was performed in 17 patients with aspirin sensitive asthma (13 women) aged 26-68 years. All subjects had aspirin sensitivity confirmed by means of oral aspirin or inhaled lysine aspirin challenge. Misoprostol (Cytotec, Searle, 800 or 1600 microg daily according to individual tolerance) or placebo were administered over a period of six weeks. Morning and evening peak expiratory flow rate (PEFR), beta(2) agonist use, asthma and rhinitis severity scores, and defaecation score were measured daily. At the beginning and end of each treatment period spirometric tests were performed and blood was taken for eosinophil count. Eight subjects took misoprostol at a dose of 800 microg and nine subjects at a dose of 1600 microg daily.

RESULTS

No differences were seen in asthma control between misoprostol and placebo except for the rhinorrhoea score which was lower on misoprostol during the period of the study.

CONCLUSION

Misoprostol in a daily dose of 800 or 1600 microg does not significantly improve asthma control in subjects with aspirin sensitive asthma.

Expression of interleukin-5 and granulocyte-macrophage colony-stimulating factor in aspirin-sensitive and non-aspirin-sensitive asthmatic airways

Increased numbers of eosinophils and mast cells in the bronchial mucosa are characteristic features in subjects with aspirin-sensitive asthma. Interleukin-5 (IL-5) and granulocyte-macrophage colony-stimulating factor (GM-CSF) are involved in the activation, maturation, and perpetuation of survival of eosinophils. Immunohistochemical techniques were therefore used to study the expression of IL-5 and GM-CSF on frozen bronchial biopsies from 13 aspirin-sensitive asthmatic (ASA) and 8 non-ASA (NASA) subjects. Aspirin sensitivity was diagnosed by lysine-aspirin inhalation provocation. ASA airways demonstrated a significant 2-fold increase in the total number of submucosal inflammatory cells expressing IL-5 (p = 0.03) and approximate 4- and 2-fold increases in the numbers of mast cells expressing IL-5 and GM-CSF (p = 0.02 and p = 0.04, respectively). There was also a 4-fold increase in the number of eosinophils expressing IL-5 (p = 0.004). These results suggest a central role for the mast cell and eosinophil in regulation of the inflammatory cell infiltrate of ASA airways by secretion of the hemopoietic cytokines IL-5 and GM-CSF.

Enhanced expression of cyclo-oxygenase isoenzyme 2 (COX-2) in asthmatic airways and its cellular distribution in aspirin-sensitive asthma

BACKGROUND

There are two isoforms of cyclo-oxygenase (COX), namely COX-1 and COX-2. COX-1 is constitutively expressed in most tissues and in blood platelets. The metabolites derived from COX-1 are probably involved in cellular housekeeping functions. COX-2 is expressed only following cellular activation by inflammatory stimuli and is thought to be involved in inflammation.

METHODS

The expression of COX-1 and COX-2 isoenzymes has been studied in the bronchial mucosa of 10 normal and 18 asthmatic subjects, 11 of whom had aspirin-sensitive asthma (ASA) and seven had non-aspirin-sensitive asthma (NASA) RESULTS: There was a significant fourfold and 14-fold increase, respectively, in the epithelial and submucosal cellular expression of COX-2, but not of COX-1, in asthmatic patients. There was no significant difference in the total number of cells staining for either COX-1 or COX-2 between subjects with ASA and NASA, but the number and percentage of mast cells that expressed COX-2 was significantly increased sixfold and twofold, respectively, in individuals with ASA. There was a mean fourfold increase in the percentage of COX-2 expressing cells that were mast cells in subjects with ASA and the number of eosinophils expressing COX-2 was increased 2.5-fold in these subjects.

CONCLUSION

COX-2-derived metabolites may play an essential part in the inflammatory processes present in asthmatic airways and development of drugs targeted at this isoenzyme may have therapeutic potential in the treatment of asthma. Mast cells and eosinophils may also have a central role in the pathology of aspirin-sensitive asthma.

Urinary leukotriene E4 levels in high-altitude pulmonary edema. A possible role for inflammation

STUDY OBJECTIVES

Inflammation may contribute to the pathogenesis of high-altitude pulmonary edema (HAPE). This study was designed to determine whether a marker of inflammation, urinary leukotriene E4 (LTE4), is elevated in patients with HAPE.

DESIGN

We conducted a case-control study to collect clinical data and urine samples from HAPE patients and healthy control subjects at moderate altitude (> or = 2727 m), and follow-up urine samples from HAPE patients following their return to low altitude (< or = 1,600 m).

SETTING

Five medical clinics in Summit County, Colorado.

PATIENTS

Questionnaire data were evaluated in 71 HAPE patients and 36 control subjects. Urinary LTE4 levels were determined from a random subset of 38 HAPE patients and 10 control subjects presenting at moderate altitude, and on 5 HAPE patients who had returned to low altitude.

MEASUREMENTS AND RESULTS

Using an enzyme immunoassay technique, urinary LTE4 levels were found to be significantly higher in HAPE patients (123 [16 to 468] pg/mg creatinine, geometric mean [range]) than in control subjects (69 [38 to 135]), p = 0.02. Following return to low altitude, urinary LTE4 levels fell significantly from 122 (41.8 to 309) to 53.6 (27.6 to 104) pg/mg creatinine (p = 0.05). Urinary LTE4 levels were not related to age, sex, time at altitude, physical condition or habitual exercise, recent use of alcohol or nonsteroidal anti-inflammatory drugs (NSAIDs), or oxygen saturation. Clinical factors associated with HAPE included male sex, regular exercise, and recent use of NSAIDs.

CONCLUSIONS

We conclude that urinary LTE4 levels are elevated in patients with HAPE, supporting the view that HAPE involves inflammatory mechanisms.

Urinary leukotriene E4 in the assessment of nocturnal asthma

BACKGROUND

Urinary leukotriene E4 (LTE4) is a marker of the body's production of cysteinyl LTs, important mediators of airway inflammation. The role of the latter in nocturnal asthma is a topic of increasing interest.

OBJECTIVE

This investigation was aimed at determining whether nighttime attacks are associated with increased release of LTs, expressed by urinary LTE4, and the relationship between the two phenomena.

METHODS

Three groups were studied: group A, seven control subjects; group B, nine asthmatic patients without nocturnal attacks; and group C, nine asthmatic patients with a comparable daytime FEV1 but who were experiencing nocturnal exacerbations (morning dips in peak expiratory flow greater than 20%). Urine was collected over 24 hours in three samples (9:00 AM to 3:00 PM; 3:00 PM to 9:00 PM; and 9:00 PM to 9:00 AM). LTE4 was measured by high-performance liquid chromatography and radioimmunoassay and expressed as nanograms per millimole of creatinine.

RESULTS

No significant differences between urinary LTE4 were noticed within groups A and B. Conversely, in group C urinary LTE4 at night (geometric mean with 95% confidence interval; 35.16 with 28.77-42.85) was significantly higher than that of the other samples (respectively 23.12 with 17.78-30.06, p less than 0.05; and 25.18 with 21.03-30.13, p less than 0.02); it was also significantly higher than in all the samples of other groups. A significant (p less than 0.02) linear correlation was observed between morning dip in peak expiratory flow and the log urinary LTE4 in the nocturnal sample.

CONCLUSION

These results indicate the role of LTs in nocturnal asthma and suggest that urinary LTE4 may be a useful marker of this condition.

Effect of endobronchial aspirin challenge on inflammatory cells in bronchial biopsy samples from aspirin-sensitive asthmatic subjects

BACKGROUND

The aspirin-induced bronchoconstriction in patients with aspirin-sensitive asthma is caused by cysteinyl leukotriene release. The cellular source of the leukotrienes is unknown. The inflammatory cell infiltrate in bronchial biopsy samples from seven aspirin-sensitive asthmatic (ASA) subjects and eight non-ASA subjects before and after local challenge with lysine aspirin was therefore examined.

METHODS

Using flexible bronchoscopy, airway mucosal biopsy samples were taken and lysine aspirin solution was placed directly onto a carina of the contralateral lung. Twenty minutes later a second series of biopsy samples was taken from the site of the local endobronchial lysine aspirin challenge. The biopsy samples were double immunostained with a rabbit polyclonal antibody to the enzyme 5-lipoxygenase and monoclonal antibodies to mast cells (AA1), neutrophils (NP57), macrophages (EBM11), T lymphocytes (anti-CD3), and total (BMK13) and activated eosinophils (EG2).

RESULTS

A decrease in both absolute mast cell numbers staining with mast cell tryptase (AA1) and the percentage of mast cells co-immunostaining with 5-lipoxygenase was seen in the ASA patients after lysine aspirin challenge compared with the non-ASA control group. There was also an increase in the numbers of activated eosinophils (EG2) in the ASA subjects compared with the non-ASA group. No changes were observed in the total numbers of macrophages (EBM11), neutrophils (NP57), total eosinophils (BMK13), and T lymphocytes (anti-CD3) after challenge with lysine aspirin.

CONCLUSIONS

The decrease in numbers of mast cells staining for tryptase and the increase in activated eosinophils after endobronchial challenge with lysine aspirin may represent degranulation of these cell types, and may be an early event associated with aspirin-sensitive reactions in ASA subjects.

Eicosanoids and asthma: an update

There have been significant advances in our understanding of the role of eicosanoids as mediators in inflammation since their discovery over 50 years ago. Our more recent understanding of asthma as an inflammatory disease has led to the appreciation of eicosanoids potentially being pivotal mediators in promoting some of the changes in asthma. Of particular importance are the cysteinyl LTs in producing bronchospasm and bronchial hyperresponsivenss, and PGE2 in modulating the bronchospastic and inflammatory response. Evidence from clinical studies suggests that other eicosanoids may also contribute, but their importance is secondary and their relative contributions vary between individuals. The development of new drugs based on our partial understanding of the role that eicosanoid mediators may play in asthma promises new approaches to the treatment of this common chronic inflammatory condition.